Counterbore



June 13, 1939. v SAXER 2,162,284

COUNTERBORE Filed June 10, 1938 J 6 6 3 l5 f/ls I4 s 0 l3 4 L J 9 l2 FIG-'7 INVENTOR ADAM E. SAXER Patented June 13, 1939 UNITED STATES PATENT OFFlCE Adam E. Saxer, Lakewood, 01110 Application Junelii, 1938, Serial No. 212,968

3 Claim.

This invention relates to adjustable counterbores, its object being to provide an improved tool of this kind adapted within a reasonable range of sizes to produce pilot and counterbore :5 holes of any desired diameter and depth, thus dispensing with the relatively large number of solid, one-piece or non-adjustable counterbores heretofore required for the same range of sizes.

A further object is to provide an improved adl justable counterbore of the character described,

said tool embodying the minimum number of parts, and all of the parts being of simple form, with the cutting parts easily replaceable or being capable of sharpening orrenewal by simple operations. A further object of the invention is to provide an adjustable counterbore which is readily adjustable and in which the cutting parts are rigidly held and are compelled to perform their proper duty with the assurance of accurate results.

Further objects are in part obvious and in part will appear more in detail hereinafter.

In the drawing, Fig. 1 represents alongitudinal sectional view on the line l-i, Fig. 2, through a tool embodying the invention;

Fig. 2 is an end view, from the bottom in Fig. 1; Fig. 3 is an end view from the top in Fig. 1; Fig. 4 is a longitudinal sectional elevation, corresponding to Fig. 1, but on the line 4-4, Fig. 5, I

showing the same tool equipped with a pilot drill and bit of a different size;

Fig. 5 is an end view, from the bottom in Fig. 4;

Fig. 6 is a cross sectional view on the line 66, Fig. 4, looking in the direction of the arrows; and

Fig. 7 is a diagram illustrating adjustment of the tool.

Counterbores of this class are used where it is desired to drill a hole of one diameter, the entrance to which is formed by a cylindrical recess or hole of larger diameter, such as a hole to receive the shank and head of a fastening bolt without any portion thereof extending above the surface of the piece. Usually the counterbore hole is approximately twiggthe diameter of the pilot hole, although the relations between the two may vary. According to present practice these counterbores are usually made in one piece or at least non-adjustable with pilot and bit portions mounted or held in fixed relation toeach other so that a difierent tool is necessary for every size and for every combination of diameters of pilot and 'counterbore holes.

The present invention provides a counterbore which includes the necessary parts for supporting and holding rigidly in fixed relation to each other (Cl. 7'l--58) a pilot drill and a cutting bit, the latter-for producing the counterbore hole. The-pilot drill may be of standard form andthus easily replaceable when dull or .worn out. The bit may be an ordinary piece of rectangular" tool steel, again of 5 standard size, and adapted to be ground for the particular diameter of counterborehole to be cut.

In the arrangement shown in-the drawing, the tool comprises a main body portion 1 provided with a shank zfladapted for-connection to the driving spindle, the shank being usually tapered as shown. ifiaid body portion {is also provided with a recessii orlsocket 3 coaxial with the axis of the shank 2 and adapted to receive the shank of the pilot drill. The drill shank and the socket 15 which receives it may also be tapered, as shown, the'body portion being provided with the usual drift pin openings 5.

The lower portion of the bodyportion I, whileit contains thesocket 3 coaxial with the axis of shank 2, nevertheless itself is eccentric to said axis, being bounded by surfaces of revolution about an axis offset with reference to theaxis of shank 2 about which the tool as a whole revolves during the drilling operation. More particularly, the body portion l is enlarged and oifset to one side, as at 6, its lower or outer end having a cylindrical outer surface 1 extending between the end shoulder or abutment 8 and an intermediate shoulder or abutment 9, thus providinga sort of head on the outer end of the body on which the bit carrier is mounted.

The bit carrier, indicated at III. is a hollow cuplike member, symmetrical around the axis of the cylindrical head I and having a strong, thick end portion II and a sleeve l2 which extends beyond the shoulder 9 and is internally threaded to receive the threaded portion of a clamping member i3 having a hex head i4.

When the supporting member III has been rotatably adjusted to bring the bit into close contacting relation with the pilot drill, it may be clamped in such position by screwing up the clamping member H by applying a wrench to the hex head thereof, another wrench being applied to the hex surfaces of the end member ll. Screwing up the members l0 and I3 causes them to clamp against the shoulders 8 and 9 and firmly fix the parts together. When fully adjusted and clamped member l3 may be further secured by screwing up the set screws 15, as will be readily understood.

The hex shaped strong end portion ll of the support III is provided with means for supporting the counterboring bit, such as a. rectangular sock- 55 at or opening I 6 in which the square shank of the bit I! may be inserted, a set screw ll being provided to hold it firmly in place. The protruding portion of the bit, indicated at Ila, Fig. 1, is ground 01! not only to provide the radially extending cutting edge l8, but to also provide the necessary clearance back of the cutting edge and at the periphery, as will be readily understood.

Figs. 1, 2 and 3 show the parts holding the maximum size of both pilot drill and bit. The pilot drill has its cutting portion extending through an opening 20 in member ll, somewhat larger than the drill itself. Also, the longitudinally extending corner edge of the bit F, indicated at 2|, Fig. 2, extends into the said opening 20 and hugs and lies alongside oi the surface of the cutting portion of the pilot drill. Consequently with the parts in the positions shown in Figs. 1 and 2, the tool, when revolved about the axis of the shank 2, will cut a pilot hole followed by a counterbore hole of approximately twice its size.

Figs. 4 and 5 illustrate the tool fitted to produce smaller pilot and counterbore holes and specifically such holes are half the diameter of the tool before described. The drill, 4a in this case, has the same size shank, but its cutting end portion lb is of half the size. The bit ilb has the same size shank where it enters the recess I, but its protruding end portion has been ground oif to form a smaller cutting end portion llc. Also, it will be understood that in Fig. 5, after inserting the proper sizes of pilot drill and bit, the member II has been adjusted around its own axis in the counterclockwise direction, Fig. 5, to again bring the longitudinally extending edge 2| of the bit into close neighboring and contacting relation with the pilot drill.

Fig. 7 is a diagram illustrating adjustment of the tool for three dinerent sizes of drill and bit, large, intermediate and small. In each case, the length of the substantially radial cutting edge of the bit, marked I8, is equal to one half the diameter of the pilot drill. The large, intermediate and small bits are respectively indicated at a, b and c, and the large, intermediate and small pilot drills at m, b1 and c1. Adjustment of the bit carrier i0 is about the axis indicated at X, while the tool as a whole, during the cuttin Operation, rotates about the axis Y.

The tool as a whole is of simple form and is capable of being set or adapted for any size of hole within a reasonable range. By selecting cutting bits of the proper length or adjusting them longitudinally of the axis, the end cutting edge of the bit may be brought nearer to or farther from the end of the pilot drill. In all cases the bit cuts right up close to the boundary of the previously cut pilot hole and a clean, true job is completed. Both the drill and the bit are readily replaceable when dull or worn.

What I claim is:

1. A counterbore comprising a holder having a shank for attachment to a spindle, said holder having a socket axially alined with said shank for receiving a drill, said holder having an outer cylindrical surface eccentric to said drill socket, a cup-shaped carrier having a sleeve portion rotatable about said cylindrical surface and having an end portion, there being an opening through said end portion through which said drill passes, there being means for mounting a cutting bit on said carrier to one side of said opening, and means for clamping said carrier in adjusted positions on said holder, the relation between the parts being such that said bit is adjustable in such a manner that it may have its cutting edge moved substantially into contact with said drill.

2. A counterbore .as in claim 1 wherein said mounting means is arranged to hold said bit.in

various adjusted positions longitudinally of said drill.

3. A counterbore, comprising a holder having a socket for receiving a pilot drill, a carrier mounted upon said holder, means for mounting a counterboring bit on said carrier wholly to one side of said drill, and said carrier being adjustable on said holder to move said bit in an are which intercepts a drill in said socket, whereby said bit may be moved substantially into contact with varying size drills in said socket.

ADAM E. SAXER. 

